Is there a relationship between delta sleep at night and afternoon cerebral blood flow, assessed by HMPAO-SPECT in depressed patients and normal control subjects? Preliminary data

We wished to explore the relationships between waking HMPAO uptake and visu ally scored polysomnography. We hypothesized that HMPAO activity would corr elate positively with slow wave sleep measures the same night. Eight unmedi cated unipolar patients with current DSM-IV major depression (17-item Hamil ton Depression Rating Scale score 21.5 +/- 2.9) and seven control subjects received polysomnography on 2 consecutive nights. On the afternoon followin g the adaptation night, subjects received cerebral SPECT, with 15 mCi Tc-99 m-HMPAO injected while subjects performed the Continuous Performance Task. Patients and control subjects did not significantly differ on demographic, polysomnographic, and SPECT variables. Slow wave sleep measures correlated positively (Spearman's) with global and regional tracer activity for depres sed (n = 8), control(n = 7) and combined groups (n = 15); in other words, t he greater the global or regional afternoon HMPAO uptake, the greater the s low wave sleep measures were the same night. In addition, the greater the w aking afternoon global or regional HMPAO activity, the faster subjects fell asleep and the less Stage 2% they had. In patients, global and regional HM PAO activity correlated positively with REM density. Positive correlations between waking tracer activity and subsequent slow wave measures are consis tent with previous hypotheses Linking slow wave sleep with brain energy con servation and restoration. Further study is needed to determine whether the se functional relationships differ in depression. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.